Smith’s Bible Dictionary
Greyhound: the translation in the text of the Authorized Version, (Proverbs 30:31) of the Hebrew word zarzir mothnayin ; i.e. "one girt about the loins." Various are the opinions as to what animal "comely in going" is here intended Some think "a leopard," others "an eagle," or "a man girt with armor," or "a zebra," or "a war-horse girt with trappings." But perhaps the word means "a wrestler," when girt about the loins for a contest.